It is well known in the art that a region having a V-shape section enriched in segregates and inclusions is formed after the completion of crystallization of the liquid metal. The region moves upwards because of the ridge, and then the impurities depart from the centre of the cast ingot and are more centralized.
What's more, the metal bound with the segregates and inclusions can not be easily separated from impurities, which will affect the improvement of the yield of metal. Currently, most of metal ingots in the world are still casted in this way, and thus a lot of metal is not recovered with a high quality to be used effectively and fully, which cause a lot of energy wasting.
In order to get clean metal, a secondary melting refining procedure, such as electroslag remelting is needed. This causes a great wasting of manpower and resource. Additionally, a great pressure is also imposed on the environment. This does not meet the requirements of energy saving and environmentally friendly development, which is the great loss of the metal smelting industry.
In the process of the secondary melting refining by electroslag remelting, a lot of electric power is required to remelt the ingot. What is worse, this is also a restriction to the large-scale industrial production, and the residue compound contains a lot of calcium fluoride which is pollutant to the environment, and thus a de-dust and a de-fluorine device are have to be arranged. In addition, because the efficiency is particularly low, especially the electric arc could seriously damage the crystallizer, a crystallizer mold in the manner of electroslag furnace remelting can only refine scores of furnace of steel, which increases the cost of production.